Fresh build...knock? (video)
Fresh build...knock? (video) I just finished up my LT1 build. Had the block assembled by the machine shop --> Manley .020 over forged pistons, Eagle 6" rods, stock crank, ARP main studs, cc306 cam. I've got TPiS/AFR 187 cc heads with Proform 1.6 rr, Trickflow 7.2" pushrods and new GM Performance parts lifters. Also did a double roller chain with Meziere water pump. It's a 95 engine if that matters.
The car idled open headers for probably 10 minutes and then I changed the oil and threw the exhaust on it. Upon start up after hooking up exhaust, I get this noise. I have no idea what this could be.
The car idled open headers for probably 10 minutes and then I changed the oil and threw the exhaust on it. Upon start up after hooking up exhaust, I get this noise. I have no idea what this could be.
I know, it doesn't sound right to be a bottom end knock. I pulled the valve covers off and saw no marks on them or the rockers. Could too much preload on the rockers cause this sound? What about timing chain making contact with the cover?
Piston slap?
Piston slap?
A mechanics stethoscope (or a piece of hose) would prove to be invaluable in this situation. A noise of that volume should be pretty easy to track down. If something were hitting the valve covers I would assume you'd be able to feel it with your hand.
What timing set are you running? If the rockers were too tight the valves would hang open and it would run poorly.
What timing set are you running? If the rockers were too tight the valves would hang open and it would run poorly.
lol you keep running it it may stop after it grind what every its hitting away. but it sounds like its hitting the value covers, take both off and then run it and see if you get that noise
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It's definitely not hitting the valve covers, already ran it with them off. It was coming from deeper down, sounded like the middle front. Tore it down to the timing chain and found wear marks on the timing cover. It's a 95 cover. I heard about it making contact but didn't feel anything while spinning it by hand so I thought I was good to go. I didn't think something like that would make that much noise.
There is no way I would ever just let it run and clearance itself. I just finished up with a rebuild and there was metal in EVERYTHING from bad mains and I'm not dealing with that again.
There is no way I would ever just let it run and clearance itself. I just finished up with a rebuild and there was metal in EVERYTHING from bad mains and I'm not dealing with that again.
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Thats the exact same thing I thought immediately when I heard the noise. You need to pull the valve cover and see if its hitting. Did you clearence those new valve covers for promags or not?
It's not coming from the valve covers, I know that for sure. They were tapping a tad, I already clearanced those. I took the timing cover off and don't see any marks at all. I would imagine even after running for 20 minutes it would show signs. I think I got something else going on here.
Nope, they were flat tops and didn't extend past the bore, they were pretty much flush with it. I didn't degree the cam, just set it to factory spec with the timing marks on the gears.
It's too fast to be valvetrain and I would even say too fast to be the piston making contact with something. I would look for the crank to be hitting something or a problem in the timing set area. Are you sure it's nothing in the clutch/flywheel area too?
It's the stock, original crank and windage tray that I took out of the engine, the crank was ground and oversized bearings were used. There was clearance just like a stock engine. Only other thing I can think of is the rods touching the pan, but once again, stock crank. I'm gonna try clearancing the timing cover and put it back together. If it still does it I'll pull the pan and see if I can find anything. I'm trying to avoid pulling the pan as its not easy to do in this car at all.